As is well known, polyamide resins find use in fibers and other broad application areas. However, they suffer from disadvantages that the dimensional stability of their moldings is poor and their electrical and other properties are greatly affected by moisture, because they have inherently high water absorption due to their structure having the amide bond. The effect of moisture on the electrical properties is important, for example, in the field where polyamides are used as a heat-sensitive element or a temperature fuse for the heating element of electric blankets and electric carpets on account of their characteristics that their impedance varies depending on the temperature and they have a sharp melting point inherent in crystalline polymers. Therefore, for such applications there are used nylon 11 and nylon 12 which are comparatively low in water absorption among the class of polyamide resins. Nevertheless, they are still susceptible to moisture and no satisfactory performance has been obtained.